Without limiting the scope of the invention, its background is described in connection with Braille display readers.
It has been estimated that, as of 1990, there were 4.3 million severely visually impaired persons in America. Of these, 12% (515,000) were "blind in both eyes" and therefore unable to use devices or computer software for magnifying images.
Over the years many aids have been developed for blind people to compensate for their lack of visual reading ability. Of these many aids, the most well known and most widely used is Braille. In standard literary Braille, letters are represented by embossed characters made up of from one to six dots arranged in a configuration of two columns of three dots each. An 8 dot Braille system (2 columns of 4 dots) has also been developed, to comprehend mathematical symbols and to permit compatibility with the ASCII character set. A blind reader usually touches Braille characters with his fingers to identify the letters and words which he "reads". Since Braille was first developed by Louis Braille in 1825, many blind persons have learned to read Braille. Therefore, dissemination of Braille texts and instructions for everyday necessities would enable Braille readers to communicate to the rest of the world. Numerous texts have already been transcribed into Braille, however, there are presently significant problems with providing and disseminating large numbers of Braille copies of textual material due to several factors. Braille literacy translates to employability; According to the American Foundation for the Blind (AFB), 85% of those using Braille as their primary method of reading are employed (Spungin, S. J., Braille Literacy-Issues for Blind Persons, Families, Professionals, and Producers of Braille. Brochure published by the American Foundation for the Blind.).
However, Braille literature in hard-copy form requires expensive printers and much more storage space than other literature, because of its bulk. An authority has also stated that the tactile readability of Braille hard-copies may begin to deteriorate after as few as 3 tactile readings.
Several systems have been developed which electronically store data representative of Braille characters and reproduce that data for a blind reader. All previous systems, however, have suffered from the drawback that they can only reproduce from a few characters to, at most, a single line of Braille. It is frequently desirable for both sighted and sightless readers to refer back to previous material on a page or on a previous page. This is especially important, of course, when studying complicated subjects. Examples of this are charts, tables, musical, and mathematical materials. Electronic Braille reproduction devices which provide only a single line do not allow a Braille reader to easily refer back to previous material or to deal with tabular or multi-line materials. Whereas in a conventional Braille book, a blind reader may skim or quickly look for previous material by reading a line or two on a page to determine the location of that material, currently available electronic Braille reproduction devices which display only a single line at a time make such reference back to previous material confusing, difficult, and time consuming. It has also been found that a Braille reader reads much more slowly when presented with a single line at a time in comparison with the speed at which the full pages of Braille books may be read.
Currently, refreshable Braille displays are usually made using either piezoelectric or electromechanical (solenoid) technologies. Typically, the products of these technologies are prohibitively expensive sources of Braille text (e.g., 1 line of 80 8-dot Braille characters for $13,000 to $15,000). Graphical (i.e., non-textual) information is not generally available either in hard-copy or refreshable form. Therefore, most blind people, even if they are literate, now rely on being read to by humans, by prerecorded audio tapes (if available), or by one of two kinds of devices with electronically synthesized speech: screen readers installed in PCs, or stand-alone scanner-OCR-readers.